SH7080 Datasheet, PDF (941/1644 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 17 Synchronous Serial Communication Unit (SSU)
(2) Data Transmission
Figure 17.5 shows an example of transmission operation, and figure 17.6 shows a flowchart
example of data transmission.
When transmitting data, the SSU operates as shown below.
In master mode, the SSU outputs a transfer clock and data. In slave mode, when a low level signal
is input to the SCS pin and a transfer clock is input to the SSCK pin, the SSU outputs data in
synchronization with the transfer clock.
Writing transmit data to SSTDR after the TE bit is set to 1 clears the TDRE bit in SSSR to 0, and
the SSTDR contents are transferred to SSTRSR. After that, the SSU sets the TDRE bit to 1 and
starts transmission. At this time, if the TIE bit in SSER is set to 1, a TXI interrupt is generated.
When 1-frame data has been transferred with TDRE = 0, the SSTDR contents are transferred to
SSTRSR to start the next frame transmission. When the 8th bit of transmit data has been
transferred with TDRE = 1, the TEND bit in SSSR is set to 1 and the state is retained. At this time,
if the TEIE bit is set to 1, a TEI interrupt is generated. After transmission, the output level of the
SSCK pin is fixed high when CPOS = 0 and low when CPOS = 1.
While the ORER bit in SSSR is set to 1, transmission is not performed. Check that the ORER bit
is cleared to 0 before transmission.
Rev. 3.00 May 17, 2007 Page 883 of 1582
REJ09B0181-0300